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Volume 26(8); August 2013

Analog Performance Analysis of Self-cascode Structure with Native-Vth MOSFETs
Dae Hwan Lee, Ki Ju Baek, Ji Hoon Ha, Kee Yeol Na, Yeong Seuk Kim
J Electr Electron Mater 2013;26(8):575-581.   Published online August 1, 2013
The self-cascode (SC) structure has low output voltage swing and high output resistance. In order to implement a simple and better SC structure, the native-Vth MOSFETs which has low threshold voltage (Vth) is applied. The proposed SC structure is designed using a qualified industry standard 0.18-㎛ CMOS technology. Measurement results show that the proposed SC structure has higher transconductance as well as output resistance than single MOSFET. In addition, analog building blocks (e.g. current mirror, basic amplifier circuits) with the proposed SC structure are investigated using by Cadence Spectre simulator. Simulation results show improved electrical performances.
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Macro Model of DWFG MOSFET for Analog Application and Design of Operational Amplifier
Ji Hoon Ha, Ki Ju Baek, Dae Hwan Lee, Kee Yeol Na, Yeong Seuk Kim
J Electr Electron Mater 2013;26(8):582-586.   Published online August 1, 2013
In this paper, a simple macro model of n-channel MOSFET with dual workfunction gate (DWFG) structure is proposed. The DWFG MOSFET has higher transconductance and lower drain conductance than conventional MOSFET. Thus analog circuit design using the DWFG MOSFET can improve circuit characteristics. Currently, device models of the DWFG MOSFET are insufficient, so simple series connected two MOSFET model is proposed. In addition, a two stage operational amplifier using the proposed DWFG MOSFET macro model is designed to verify the model.
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Study on the Design of DC-DC Converter for Super Junction MOSFET Battery Charger of Electric Vehicles
Bum June Kim, Yong Sung Hong, Gwan Pil Silm, Ey Goo Kang
J Electr Electron Mater 2013;26(8):587-590.   Published online August 1, 2013
Release competition and development of eco-friendly vehicles have been conducted violently also automaker, it will be a high growth industry of the charger and battery, which is the driving source of the motor of an electric vehicle. Reduces the on-resistance power elements DC - DC converter for battery charger for electric vehicles, must minimize switching losses. Should have a low on-resistance power than existing products. Compare the Super Junction MOSFET and Planar MOSFET, As a result, super junction MOSFET improve on about 87.4% on-state voltage drop performance than planar MOSFET.
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The Effect of Zn/Sn Different Raito of InZnSnO Thin Films Prepared by RF Magnetron Sputtering
Ki Hwan Kim, Maryane Putri, Chang Young Koo, Jung A Lee, Jeong Joo Kim, Hee Yong Lee
J Electr Electron Mater 2013;26(8):591-596.   Published online August 1, 2013
Indium Zinc Tin Oxide (IZTO) thin films were developed as an alternative to Indium Tin Oxide (ITO) thin films. ITO material which has been acknowledged with its low resistivity and optical transparency of 85-90% has been used as major transparent conducting oxide (TCO) materials. However, due to the limited source, high price, and instability problems at high temperature of indium, many researches has been focused on indium-saving TCO materials. Mason Group of Northwestern University was reported to expand the solubility limit up to 40% by co-doping with 1:1 ratio of Zn+2 and Sn+4 ions. In this study, the properties of IZTO thin films corresponding to Zn/Sn different ratio were investigated. In addition, the effect of substrate temperature variable to the structural, optical and electrical properties of IZTO thin films was investigated.
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Insulation Materials : Regular Paper ; Effects of Freshwater Flooding on Properties of CSPE with Number of Dried-Days
Myeong Kyun Kang, Jung Hoon Lee, Seung Hoon Lee, Jun Soo Jeon, Young Park, Ki Yub Park, Kyu Won Jeong, Yong Deok Shin
J Electr Electron Mater 2013;26(8):597-601.   Published online August 1, 2013
The accelerated thermal aging of a CSPE were carried out for 0, 80.82, 161.63 days at 100℃, which are equal to 0, 40 and 80 years of aging at 50℃, respectively. The volume electrical resistivities of the seawater and freshwater flooding were measured through 3-terminal circuit diagram. The volume electrical resistivities of the 0y, 40y and 80y were 2.454×1013∼1.377×1014Ω?cm, 1.121×1013∼7.529×1013Ω?cm and 1.284×1013∼8.974×1013Ω?cm at room temperature, respectively. The dielectric constant of the 0y, 40y and 80y were 2.922∼3.431, 2.613∼3.285 and 2.921∼3.332 at room temperature, respectively. It is certain that the ionic (Na+, Cl-, Mg2+, SO4 2-, Ca2+, K+) conduction current was formed by the salinity of the seawater. The volume electrical resistivity of the cleaned CSPE via freshwater trends slightly upward with the number of dried days at room temperature. As a result, the CH2 component of thermally accelerated aged CSPE decreased after seawater and freshwater flooding for 5 days respectively, whereas the atoms such as Cl, O, Pb, Al, Si, Sb, S related with the conducting ion (Na+, Cl-, Mg2+, SO4 2-, Ca2+, K+) component increased relatively.
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Thin Films and Sensors : Regular Paper ;The Characteristics of Mg0.1Zn0.9O Thin Films on PES Substrate According to Fabricated Conditions by PLD
Sang Hyun Kim, Hyun Min Lee, Nak Won Jang, Mi Seon Park, Won Jae Lee, Hong Seung Kim
J Electr Electron Mater 2013;26(8):602-607.   Published online August 1, 2013
Concern for the TOS (Transparent Oxide Semiconductor) is increasing with the recent increase in interest for flexible device. Especially MgZnO has attracted a lot of attention. MgxZn1-xO, which ZnO-based wideband-gap alloys is tuneable the band-gap ranges from 3.36 eV to 7.8 eV. In particular, the flexible substrate, the crystal structure of the amorphous as well as the surface morphology is not good. So research of MgZnO thin films growth on flexible substrate is essential. Therefore, in this study, we studied on the effects of the oxygen partial pressure on the structural and crystalline of Mg0.1Zn0.9O thin films. MgZnO thin films were deposited on PES substrate by using pulsed laser deposition. We used XRD and AFM in order to observe the structural characteristics of MgZnO thin films. UV-visible spectrophotometer was used to get the band gap and transmittance. Crystallization was done at a low oxygen partial pressure. The crystallinity of MgZnO thin films with increasing temperature was improved, Grain size and RMS of the films were increased. MgZnO thin films showed high transmittance over 80% in the visible region.
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Thin Films and Sensors : Regular Paper ;Optimized for Low-temperature Sintering of TiO2 Paste with TTIP
You Ra Jung, Hal Bon Gu, En Mei Jin
J Electr Electron Mater 2013;26(8):608-613.   Published online August 1, 2013
In this paper, the low-temperature sintering of TiO2 is approached to solve the problem of high temperature sintering which decreases the interconnection between particles or between substrate and particle. TiO2 paste is prepared with Titanium (Ⅳ) isopropoxide as the precursor material and calcinate at different conditions (low temperature). In the results, since the changing of temperature and time of sintering, crystalline phase do not change and the intensities of anatase, rutile phase are higher. At 110℃, 7 h sintering condition, crystalline size of anatase and rutile phase are the smallest which are 13.07 and 17.47 nm, respectively. In addition, the highest zeta potential is about 32.77 mV and the repulsive force increases thus leading to the best of the dispersion characteristics between TiO2 particles. Futhermore, DSSCs at that condition exhibits the highest efficiency with the values of Voc, Jsc, FF and η are 0.69 V, 8.60 mA cm-2, 67.93% and 4.06%, respectively.
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Optical Properties of Color Conversion Lens for White LED Using B2O3-Bi2O3-ZnO Glass
Yoo Jin Chae, Mi Jai Lee, Jin Ho Kim, Jong Hee Hwang, Tae Young Lim, Hee Suk Jeong, Young Sik Lee, Deuk Jung Kim
J Electr Electron Mater 2013;26(8):614-619.   Published online August 1, 2013
Recently, remote phosphor is reported for white LED enhancing of phosphor efficiency compared with conventional phosphor-based W-LED. In this study, Remote phosphor was produced by screen printing coating on glass substrate with phosphor contents rated paste and heat treatment. The paste consists of phosphor, lowest softening glass frit and organic binders. Remote phosphor can be well controlled by varying the phosphor content rated paste. After mounting remote phosphor on top of blue LED chip, CCT, CRI, and luminance efficiency were measured. The measurement results showed that CCT, CRI. and luminance efficiency were 6,645, 68, and 1,161 n/W in phosphor 80 wt.% remote phosphor sintered at 600℃.
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Nano and Oxide Electronics : Regular Paper; Regular Paper Fabrication of CNT/PVDF Composite Film and Its Electrical Properties
Sunwoo Lee, Nak Chun Jung
J Electr Electron Mater 2013;26(8):620-623.   Published online August 1, 2013
The carbon nanotube / poly-vinylidene fluoride (CNT/PVDF) composite films for the nano-generator devices were fabricated by spray coating method using the CNT/PVDF solution, which was prepared by adding PVDF pellets into the CNT dispersed N-Methyl-2-pyrroli-done (NMP) solution. The flexible CNT/PVDF composite films were investigated by the scanning electron microscopy, which revealed that the CNTs were uniformly dispersed in the PVDF matrix and thickness of the films was approximately 20 jim. Fourier transform infra-red spectra were used to investigate crystal structure of the as-spray-coated CNT/PVDF films, and we found that they revealed extremely large portion of the f3 phase PVDF. The capacitance of the CNT/PVDF films increased by adding CNTs into the PVDF matrix, and finally saturated. However, the resistance didn`t show any saturation effect in the CNT concentration range of 0- 4 wt%. Finally, the resulting nano-generator devices revealed reasonable current output after given mechanical stress.
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Technology Education : Regular Paper ; Evaluation of Thermography Camera Using Molded Optical Lens for Medical Applications
Seong Mi Ryu, Hye Jeong Kim
J Electr Electron Mater 2013;26(8):624-628.   Published online August 1, 2013
With the recent development of less-costly uncooled detector technology, expensive optics are among the remaining significant cost drivers in the thermography camera. As a potential solution to this problem, the fabrication of IR lenses using chalcogenide glass has been studied in recent years. We report on the molding and evaluation of a ultra-precision chalcogenide-glass lens for the thermography camera for body-temperature monitoring. In addition, we fabricated prototype thermography camera using the chalcogenide-glass lens and obtained the thermal image from the camera. In this work, it was found out that thermography camera discerned body-temperature between 20 and 50℃ through the analysis of thermal image. It is confirmed that thermography camera using the chalcogenide-glass lens is applicable to the body-temperature monitoring system.
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Light Source and Application Technology : Regular Paper ;A Study on the Efficiency of a High Power Factor LED Driver Circuit
Dong Won Lee, Byung Cheul Kim
J Electr Electron Mater 2013;26(8):629-634.   Published online August 1, 2013
The rectified voltage supplied to LED lamp is used in load and then the surplus voltage can be produced in LED lighting. In this case, LED lighting is proposed that can recyclable the excess voltage to supply power to the controller.
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Light Source and Application Technology : Regular Paper ;Generating Characteristics of EYE-type Piezoelectric-generator Using Tension
Yong Woo Ha, Sung Su Jeong, Na Lee Kim, Myong Ho Kim, Shin Chul Kang, Tae Gone Park
J Electr Electron Mater 2013;26(8):635-639.   Published online August 1, 2013
Generating output characteristics of a EYE-type piezoelectric generator depending on ceramic size and materials of the elastic body were studied. EYE-type piezoelectric-generating device consist of the ceramic was attached between the both elastic body. piezoelectric-generating is that if the tension occurred at both ends of an elastic body, the piezoelectric effect occurs at ceramics through the form change of the elastic body. The structure of this EYE-type generator use various area. than a existing type generator, because the ceramic position of the directly force at does not apply. Resonance and output characteristics of the generator were analyzed by using FEM program. Generators were fabricated on the basis of analyzed results and attached on a frequency controllable vibrator to measure output characteristics. Also, the experimental results were compared with the simulated results. As a result, output characteristics of the generator increased depending on the increase in ceramic thickness. In case of increase in ceramic width, resonance frequency of the generator also decreased.
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